pressure-stream

call an async function for each data event into through stream. manage concurrency as back pressure.

var pressure = require('pressure-stream');
var split = require('split2');
var request = require('request');


var concurrency = 100  // never ever do more than 100 requests at a time.

process.stdin.pipe(split())
.pipe(pressure(function(data,cb){
  request(data,function(err,res,body){
    cb(err,body)
  });
},concurrency)).pipe(process.stdout);

API

pressure(fn,opts)

• fn is the data handler it is always called with 2 arguments
  • fn(data,cb)
• when you are done with the the handler call cb(err,data)
  • if err is passed back with cb "error" will be emitted on the stream
  • data passed back on this stream will be emited as data

options

• concurrency
  • the maximum number of concurrent data handlers the stream will execute.
  • defaults to 10